Microscopic colitis
Content date: 10 November 2026
The colon may look normal during colonoscopy, but biopsies reveal inflammation. This is a treatable condition that differs from IBS and needs its own treatment plan.
Your next step
Record episodes of diarrhea and bring your medicine list to your review, without stopping medicines yourself.
Get urgent help: Fainting, markedly reduced urine, inability to drink, severe persistent pain, or obvious heavy bleeding.
Understanding the condition: why “microscopic”?
- The colon absorbs water from bowel contents to form stool. In microscopic colitis, inflammation of its lining affects water handling, causing recurrent watery diarrhea. “Microscopic” describes how the inflammation is identified under a microscope; it does not mean symptoms are mild or unimportant.
- There is a lymphocytic type, with increased numbers of certain immune cells, and a collagenous type, with thickening of a thin layer beneath the lining. Symptoms and treatments are similar. There is no single known cause for everyone; immunity, genetic susceptibility, smoking and certain medicines may contribute. Taking a medicine associated with the condition does not alone prove it caused your disease.
How does it differ from other conditions?
- Diarrhea is usually non-bloody and may wake you at night or cause urgency and stool leakage. Symptoms may come and go or persist for weeks or months. It is not an infection that spreads to others, is not a type of irritable bowel syndrome, and is not known to increase bowel cancer risk.
- The lining can look normal to the eye during colonoscopy, so a “normal colonoscopy” does not rule it out if appropriate biopsies were not taken. Treatment aims to reduce diarrhea, restore sleep and activity, and maintain hydration and nutrition. Good control is possible; recurring symptoms may need an adjusted plan or maintenance treatment.
Why are biopsies necessary?
- The colon lining may look completely normal. Small samples are taken during colonoscopy and examined under a microscope.
- We may also look for infection, celiac disease or other causes of diarrhea according to your symptoms. Visible blood in stool needs assessment and should not automatically be attributed to this condition.
How is it treated?
- Budesonide is a commonly used, effective treatment prescribed by your doctor. Symptoms may return after it finishes; you may then need a different plan or maintenance treatment at a dose chosen by your doctor.
- Some people benefit from an anti-diarrheal medicine or a medicine that binds bile acids inside the bowel if these contribute to diarrhea. Do not start these yourself, particularly if you have fever, blood or severe pain.
What can I do at home?
- Drink fluids regularly and use oral rehydration solution for significant fluid loss if your team recommends it. Follow any fluid restriction for heart or kidney disease.
- Temporarily reduce caffeine and sweeteners such as sorbitol, and review milk if you notice it worsens diarrhea. Do not exclude whole food groups without a reason.
- Record daytime and nighttime bowel movements, dizziness or reduced urine, and how symptoms affect your activities.
Review medicines without stopping them yourself
- The condition may be associated with some painkillers, acid-suppressing medicines and other drugs, but an association does not prove your medicine is the cause.
- Bring a complete list of medicines and supplements. Your doctor balances their benefits against the possibility of switching them. Stop smoking.
- A relapse does not mean treatment has permanently failed. Return to the clinic to adjust the plan rather than repeating steroids yourself.
When to get help
Fainting, markedly reduced urine, inability to drink, severe persistent pain, or obvious heavy bleeding.
Diarrhea continuing after treatment, returning after stopping medicine, or weight loss; fever or blood needs prompt assessment.
Guides for your care journey
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